Planting Emerald Green Arborvitaes

Hello:

I want to screen the rear of my yard with Arborvitaes. My yard was leveled last year and right now I have a 2' high retaining wall made out of concrete block. Within this wall there is 24 inches of planting area before a 1 foot wood retaining wall separates my yard from my neighbors. The wood wall is sunk down 6 inches and my neighbors' yard is opposite that. The length of this area is 80'. I have several questions regarding the planting of the arborvitaes:

Is this enough space to plant the arborvitaes?

Will the roots be ok since there is the 6" wall under the surface separating my yard from my neighbors?